package dj.utils;

import java.io.File;
import java.security.MessageDigest;

import dj.Constant;

public class StringUtils {

	/**
	 * 字符串为 null, "null", "undefined" 时 返回 "" 字符串
	 * 
	 * @param s
	 * @return
	 */
	public static String isNull(String s) {
		if (null == s || "".equals(s.trim()) || "null".equals(s.trim()) || "undefined".equals(s.trim())) {
			s = "";
		}
		return s;
	}

	public static String getSeralNum(String key) throws Exception {
		String num = "0";
		String seralNumFilePath = Constant.TOMCAT_PATH + "WEB-INF" + File.separator + "classes" + File.separator;
		PropertiesOperator seralnum = new PropertiesOperator(seralNumFilePath + "serialnum.properties");
		num = seralnum.getValue(key);
		seralnum.setValue(key, (Integer.parseInt(num) + 1) + "");
		seralnum.saveFile("saveFile");

		return num;
	}

	/***
	 * MD5加码 生成32位md5码
	 */
	public static String string2MD5(String inStr) {
		MessageDigest md5 = null;
		try {
			md5 = MessageDigest.getInstance("MD5");
		} catch (Exception e) {
			System.out.println(e.toString());
			e.printStackTrace();
			return "";
		}
		char[] charArray = inStr.toCharArray();
		byte[] byteArray = new byte[charArray.length];

		for (int i = 0; i < charArray.length; i++)
			byteArray[i] = (byte) charArray[i];
		byte[] md5Bytes = md5.digest(byteArray);
		StringBuffer hexValue = new StringBuffer();
		for (int i = 0; i < md5Bytes.length; i++) {
			int val = ((int) md5Bytes[i]) & 0xff;
			if (val < 16)
				hexValue.append("0");
			hexValue.append(Integer.toHexString(val));
		}
		return hexValue.toString();

	}

	/**
	 * 加密解密算法 执行一次加密，两次解密
	 */
	public static String convertMD5(String inStr) {

		char[] a = inStr.toCharArray();
		for (int i = 0; i < a.length; i++) {
			a[i] = (char) (a[i] ^ 't');
		}
		String s = new String(a);
		return s;

	}

	public static String encrypt(String str) {
		String s = convertMD5(string2MD5(str));
		return s;
	}

	// 测试主函数
	public static void main(String args[]) {
		String s = new String("123456");
		System.out.println("原始：" + s);
		System.out.println("MD5后：" + string2MD5(s));
		System.out.println("加密的：" + convertMD5(string2MD5(s)));
		System.out.println("解密的：" + convertMD5("EDGM@MAMABDACFDLLG"));
	}

}
